Multiple channel telegraph system



July 4, 1939. F. L. HENDERSON MULTIPLE CHANNEL TELEGRAPH SYSTEM Filed Sept. 25, 1937 2 Sheets-Sheet 1 FIG. 1.

FIG. 2.

5 /Z l3 l5 /6 7/8 I. Z ZZZ8Z4 552627282930 m R om n Y N ND mfi nm w, [m W F a a a m m 8 7 W 5 4 in Z July 4, 1939. F. HENDERSON MULTIPLE CHANNEL TELEGRAPH SYSTEI 2 Sheets-Sheet 2 Filed Sept. 25, 1937 FIG. 4.

/ 2 3 4- 56 7 8 8 l0 lZ/3/4/5/6/7/8 -9ZOZ/2ZZ3242526'27282-930 r w m 7 00 o o o o o 0 WM a 00 N o N 00 W o C o oo 7 H 5 O0 0 w m o 0 00 00 O 0 00 o 00 0 0 0 00 00 o o O O O 0 O 0 0o 00 00 o O 0 0 0O (B (B ATTCRNEY Patented July 4, 1939 2,164,920 MULTIPLE CHANNEL TELEGRAPH SYSTEM Forest L.

to All America Henderson, Stamford, Conn, assignor Cables,

Incorporated, New

York, N. Y., a corporation of New York Application September 25, 1937, Serial No. 165,656

9 Claims.

My invention relates to telegraph systems and more particularly to telegraph systems for multiple channel transmission.

Telegraph systems in which the same line is used for the transmission of signals on two or more channels are known. In these known systems, however, either the individual time for transmitting one message is necessarily increased due to the interposition of the other message, or

the length of the signal impulse for each of the characters of the two transmitted codes is shortened. In accordance with my invention, however, the signals on one channel may be transmitted at normal speed and the other channel interposed upon the line during a certain type of signal element transmission.

This object is achieved by transmitting as the elements of one signal code, unit or signal character element composed of short impulses of one 10 polarity and space or no current intervals, in-

stead of the usual positive and negative signal character elements. A second signal channel is composed of signal characters comprising current impulse elements of the opposite polarity and space or no current impulses. In order that the speed of transmission of the first channel may not be interfered with, the signal character elements of the second channel signal are impressed upon the line during the spacing or no current intervals of the first channel. Since an equi-unit code such as the five unit code is composed substantially of fifty percent positive and fifty percent negative current impulses, the system in accordance with my invention permits ap- Il proximately fifty percent increase capacity of the line without involving any increase in speed of transmission.

Furthermore, in submarine cable circuits employing cable code signals an increase of capacity may be obtained in accordance with my invention without any increase in speed, by using a system similar to that outlined above. This may be seen when it is considered that in the cable code ordinarily used the characters average 3.? center holes whereas with my system, as outlined above, three unit letters may be transmitted in a space of 10 center holes, or 3.3 center holes per character. It accordingly can be seen that transmission in accordance with the system of my invention may be used to increase the capacity of a cable, for example a submarine cable line using this system instead of the normal submarine cable code.

It is an object of my invention to devise a no system using ordinary telegraph equipment which permits multiple channel transmission over a single transmission line.

It is a further object of my invention to transmit two channels over a single transmission line, utilizing current elements of one polarity and spaces of no current to represent one signal channel, and current impulses of the opposite polarity and no current space intervals to represent the other channel, and to transmit one channel character during only the space or no current interval of the other channel.

It is a further object of my invention to control such a transmission system by means of tape control transmitters and to receive these signals by means of a suitable recorder.

It is a further object of my invention to devise a suitable transmitting system for multiple channel transmission in accordance with my invention.

It is a still further object of my invention to devise a suitable receiving arrangement for receiving and distinguishing the signals transmitted in accordance with my invention,

Other further objects may be presented in the following complete description given in conjunction with the accompanying drawings, in which Fig. 1 represents a transmission system for transmitting multiple channel signals in accordance wtih my invention;

Fig. 2 represents a perforated control tape for controlling the transmitter system disclosed in Fi 1;

Fig. 3 shows diagrammatically a receiver for receiving multiple channel signals in accordance with my invention, and

Fig. 4 represents a graph of the received signals and the perforated tape from channels I and 2.

For purposes of illustration I have chosen to show a system using a five unit code composed of space elements and positive elements which may be designated channel I, and an additional five unit code composed of space elements and negative current elements which may be designated as channel 2. The additional five unit code of channel 2 is transmitted during the space element of channel I. However, it is evident that the order of the code elements may be reversed, for example, space and a negative current element may be used for channel I, and space and a positive element for channel 2.

In the illustrated example, the operation is described in connection with apparatus normally associated with the operation of submarine cables but it should be clearly understood that 55 the same principles apply as well to land line operation.

Referring more particularly to the drawings, Figs. 1 and 2 represent the transmitter and the tape used for controlling the transmission in accordance with my invention. The perforated tape used for transmission on each channel is prepared with the perforations lengthwise and not across the tape, as can clearly be seen in Fig. 2.

The control tape for transmission of signals in both channels is prepared with perforations for both the normal, positive and negative signal elements as in an ordinary controlled transmitter. However, in channel I the dash or negative current perforations, and in channel 2 the dot or normally positive element perforations, are not sent through the line but are used for local control purposes.

The transmitter diagrammatically illustrated in Fig. 1, is a step-by-step transmitter such as described in the patent to W. F. Cassidy, Jr., Patent No. 1,895,094, patented January 24, 1933. Transmitter II is used for transmission over channel I, and transmitter 2| is used for transmission over channel 2.

Assume that the perforator slips of both channels have been fed forward by the operating mechanism of the transmitters until the center hole I of the perforator slips, as shown in Fig. 2, has reached a position for operation of the transmitters. Relays I2, I 3, 22 and 23 are polar relays neutrally biased. Since as shown in Fig. 2, the center holes I of both tape transmitters are perforated for dash signals, dash peckers 21 and 22 operate simultaneously, marking relays I3 and 23 and spacing relays I2 and 22. When relay I3 operates, it closes the operating circuit of transmitter operating magnet 2 through vibrating fork 5 and contact B of the vibrating fork. The operation of relay 23 closes a circuit through the spacing contact of relay I2 and the coil of dash relay 24 which operates to send a dash over line 30 for channel 2, and since the relay I4 for channel I was not operated a space element would be received at the receiving station in channel I.

Center hole 2 of both transmitter tapes is next presented at the transmitter, operating peckers 21 and I 2. Relays I2 and I3 remain on the marking and spacing contacts respectively, relay 22 marks and relay 23 spaces. When relay 23 spaces, the relay tongue of relay 24 returns to its spacing contact. Consequently space elements are transmitted to the line in both. channels.

Center hole 3 next is advanced into position and dot peckers I1 and I2 mark relays I2 and 22, and space relays I3 and 23. Relay I2 operates dot relay I4, sending a dot to line for channel I. Relay I3 opens the circuit to operating magnet 2 of transmitter 2. Since the operating magnet was not operated, center hole 4 of channel I next arrives in position, transmitter for channel 2 having been stopped by the opening of the magnet circuit by relay I3, and dot pecker I1 operates with relay I2 marking and relay I3 a spacing from the previous operation of center hole 3 and another dot goes to the line for channel I. Center hole 5 of channel I next arrives in position and center hole 3 of channel 2 is still in position as a result of the operation from center hole 3 of channel I. Dash pecker 21 and dot pecker I2 operate marking relays I3 and 22, and spacing relay I2 and 23, thus sending a space to line for both channels. When relay I3 marks, the transmitter operating magnet 2 is again in a closed circuit and starts to feed the channel 2 perforated slips when the fork 5 again contacts with contact B.

Center holes 6 of channel I and 4 of channel 2 arrive in position with peckers 21 and 22 operating, causing the same sequence of events as oc-' curred when the center holes I of both channels passed through the transmitters. Thus it can be seen that channel 2 tape is operated only during the period that positive impulses are not being sent to the line on channel I. The tape for channel 2 is shown in segments arranged opposite the points in the tape of channel 2 at which this tape will be stepped forward to illustrate this point, as can clearly be seen by reference to Fig. 2. The sequence of operation in transmission may be traced through step-by-step for the other center holes from 7-30 in channel I. In Fig. 2, tapes for channel I is shown for transmitting six letters, and it can be seen that three letters may be transmitted on the same line in channel 2 during the period of transmitting the first six letters. It is thus clear from this example, that in accordance with my system the transmission line capacity may be increased approximately fifty percent as illustrated by the above description.

The receiving circuit is now described in connection with Figs. 3 and i. The apparatus disclosed in Fig. 3 is a circuit known as a gold wire receiving relay, in which the receiving tongue operates between dot and dash contacts and is actuated by signals through a coil placed between magnets and connected to the tongue by means of silk reins. This relay in turn operates what is commonly called an automatic perforator, which is controlled by a vibrating fork 35. This fork vibrates in step with the incoming signal making contact on its inside contacts C and D at the center hole speed of the circuit. It is actu-= ated at circuit speed by having its actuating coil 36 energized from a relay 31 operating in parallel with the dot relay 38. The perforator magnets 40 4|, 42 and 43 when energized operate punching levers (not shown) which cause perforations to be made in the received tape, as shown in Fig. 4, by the tape for channel I and channel 2. When the space magnets M and 43 operate, they also feed the tape forward one center hole through a well known type of ratch feed mechanism (not illustrated).

Turning now to Fig. 4, the upper curve 5) represents the incoming signals obtained as a result of the transmission of signals in channels I and 2, previously described and illustrated in Fig. 2.

Turning more specifically to Fig. we will assume first that relay 3| is stationary momentarily, with dot relays 38 and 39 on their spacing contacts. The vibrating fork 35 when making contact at C and D, operates perforators AI and 43, causing them to punch center holes only in slip 6| of channel I and slip 62 of channel When the dash impulse of channel 2 arrives, as shown in the curve 60, relay 3.) marks when the tongue of relay 3I makes contact on its dash side. Perforators M, 42 and 43 are actuated, resulting in a dash perforation in channel 2 as well as a center hole perforation in both channels and the equivalent of a space for slip fiI of channel I. The next element arriving is a space element for center hole 2 and only space magnets M and 42 are operated, resulting in center holes in perforator slips for both channels with a space on the dot side for channel I and on the dash side for channel 2.

The next element arriving is a positiveor dot element on channel I as shown in the curve 60. This operates relay 38 which leaves its spacing stop, breaking the circuit through space magnet 43 and stopping the operation of channel 2 perforator. When relay 33 marks, dot perforator magnet 40 operates also 4| and center hole 3, and dot perforation in slip 6| is completed. Slip 62 is stationary in channel 2 perforator with only the two center holes punched. The succeeding element is also a dot positive element of channel 1 corresponding to center hole 4, and as relay Q is still on marking the resultant action is the same for center hole 3 of channel I.

The next element to arrive is a space element for both channels completing the five elements of the letter N for channel i. The tongue of relay 3| breaks its dot contact and returns to a neutral position, permitting the tongue of relay 38 to fall back on its space contact, cutting olf the dot magnet 40 and cutting into circuit space magnet 43 through the spacing stop S. This permits slip 3 of channel 2 to feed forward and center hole 3 of channel 2 is punched. As the circuit through the dot magnet 40 is broken a space also occurs for center hole in slip SI of channel I. Received element 6 next arrives and is a dash element operating relay 39. Magnets 4!, 42 and 43 are operated, completing center hole 4 and dash perforation in channel 2, and a space element for center hole 6 in channel I. The next element to arrive is a space element for both channels and relay 39 spaces, permitting magnets 4| and 43 to operate on the next vibrating fork contact, and completing center hole 5 in channel 2 for the letter D, and center hole 1 in channel I.

The succeeding operations for each received element are similar to those outlined in detail above. Slip 6| of Fig. 4 corresponds to the received signals of channel I, and slip 3 of channel 2 can be run through a five unit printer for recording purposes or the dot side of relay P can be utilized to print direct on a five unit printer for channel I and the dash side of relay 3| connected to a signal storage device from which a five unit printer could be operated upon the completion of the storage of each five elements in channel 2.

The operation of the system is clearly outlined above in the description, and further specific discussion is unnecessary. However, the specific ex amples outlined in connection with this descrip tion are to be considered only as illustrated examples of the operation of my system. It is clear to anyone skilled in the art that other forms of transmitters and receivers could be easily modified to operate to transmit two signals in multiple channel arrangements in accordance with the disclosure of my invention.

While'I have described a particular embodiment of my invention for illustrative purposes, it should be understood that various modifications and adaptations thereof may be made within the spirit of the invention as set forth in the ap pended claims.

I claim:

1. In a telegraph transmission system, a first tape controlled transmitter operating to transmit signal elements of one polarity and spaces upon a transmission line, a second tape controlled transmitter operating to transmit signal elements of the opposite polarity and spaces upon said line, and means controlled by said first transmitter to condition said second transmitter for operation only during the time said first transmitter is transmitting spaces.

ZIA telegraph communication system, com prising two transmitters, the first transmitter being operated to transmit dot indicating current impulses and spaces, and the second being operated to transmit dash indicating current impulses and spaces, and means under control of one of said transmitters for blocking the operation of said other transmitter at times when current impulses are being transmitted on said one transmitter.

3. In a telegraph system, means for transmitting in continuous succession a code message comprising multi-unit characters composed of current impulses of one polarity and intervals of no current, means for transmitting a second code message comprising multi-unit characters composed of current impulses of the opposite polarity and intervals of no current, and means under control of said first named means for conditioning said second code transmitter for transmission only during the intervals of no current of said first named code message.

4. A telegraph system comprising a transmitter for transmitting multi-unit code signals composed of positive current elements and space elements, a second transmitter for transmitting multi-unit code signals composed of negative current elements and space elements, and means for controlling said second transmitter so that said second transmitter operates only when said first transmitter is transmitting space elements.

5. A telegraph system comprising a transmitter for transmitting multi-unit code signals composed of negative current elements and space elements, a second transmitter for transmitting multi-unit code signals composed of positive current elements and space elements, and means for controlling said second transmitter so that said second transmitter operates only when said first transmitter is transmitting space elements.

6. In a telegraph communication system for communicating by code signals, comprising characters composed of different elements, means for transmitting on a single line two separate code messages, one of said codes comprising current elements of one polarity and no current spaces each element being of substantially equal time duration and the other code message comprising current elements of the opposite polarity and no current spaces of substantially the same time duration as said one code elements, means coupled to said line for receiving said messages, signal distinguishing means in said receivers responsive to the polarity of the current elements received, and means in said receiver for recording separately said separate code messages.

7. The method of multiple channel telegraph signaling over a single line, comprising transmitting a first signal comprising elements of cur rent of one polarity and no current spaces, transmitting a second signal comprising elements of the opposite polarity and no current spaces only during the time that spaces of said first named signal are being transmitted, and receiving and distinguishing between. said first and second signals.

8. In a telegraph system, means for producing signals of two messages, one message signal comprising current impulses of one polarity and no current spaces said impulses each being of substantially equal lengths and the other message signal comprising current impulses of the opposite polarity and no current spaces of substantially the same length as said one message impulses, transmitter means for applying said first named message signals to a line, other transmitter means cooperating with said first named transmitter means for applying said second named message signals to said line, and means for operating said second transmitter means in response only to the no current spaces of said first message signal means.

9. In a telegraph system as claimed in claim 8, a receiver coupled to said transmission line for receiving said message signals, and means 00- operating with said receiving means for discriminating between said received message signals and separately recording them.

FOREST L. HENDERSON. 

